The invention relates to a device and a method for measuring the elastic and elasticoviscous deformability of skin, comprising a measuring probe having a path-measuring device for measuring the deformation path of the skin surface and an electronic evaluating device, as well as to a method for measuring the elastic and plastic deformability of the human skin by pressurizing skin via a measuring probe and by measuring the deformation of the skin in response to the pressure load by measuring the deformation path.
In dermatology and cosmetics it is often necessary to perform measurements of the elasticity of skin in order to be able to check the success of therapies or the success of cosmetic preparations.
From German Patent 29 09 092 a device for measuring the elasticity of the human skin is known which includes a sensor adapted to be pressed o the skin surface with a predetermined pressure. In this device, pressure is exerted on the sensor by a presettable weight and the path of resilient intrusion of the sensor into the skin surface to be checked is determined by means of a path-measuring device. Alternatively, it is possible to provide the tip of the sensor with a suction bell that is depressurized, so that not only a pressure resistance test but also a stress test may be performed by means of the sensor. In this case, the sensor firmly adheres to the skin surface and is subsequently loaded by a weight via a turn roll such that it exerts a pulling force on the skin surface. In doing so, the path of displacement of the sensor is measured in dependence on the pulling force by means of an electronic evaluating device. Such a measuring device is mechanically complex, the measuring itself being difficult to perform for reasons of the low weights used, since for a measuring the skin surface to be checked has to lie absolutely still. Moreover, no satisfactory precision can be obtained with the device described, since at the low pressures used and the low bearing weights resulting therefrom, interference factors like the friction of the cord and the friction of the bearing of the cord roll, as well as movements of the skin surface, will be reflected in the measuring. Finally, it is necessary to have the skin surface to be checked lie in a horizontal position, because of the weights used.
Further, a device for measuring the elasticity of the human skin is known from European Patent 0 255 809 wherein a vacuum bell is placed on the skin surface to be examined, which bell is connected via a duct to a vacuum gauge device and a measuring chamber in which a piston is movably arranged. In order to depressurize the suction bell, the piston of the measuring chamber is moved backward from a defined zero position to a predetermined vacuum and the necessary suction volume, which depends on the volume of skin bulging into the suction bell, is determined at the measuring chamber. This device has the disadvantage of requiring a comparatively large skin surface for measuring the volume, thus making it impossible to measure smaller skin surfaces or different skin layers, e.g. the uppermost skin layer that is of particular importance for cosmetics.
From German Laid Open 36 12 312 a device for examining the elasticity of the skin surface is known in which the deformation of the skin is caused by subjecting the skin surface to a gas flow. The degree of deformation is determined by the reflection of light at the deformed location. A light barrier is not provided.
From French Laid Open 26 03 183 a measuring device for measuring skin characteristics is known in which an element is pressed into the skin under the action of a spring, which element enters the skin in different depths depending on the deformation of the skin. The end of the element opposite the skin influences the path of light of a light barrier in dependence on the depth of intrusion into the skin.
Further, an optic sensor is known (German Patent 87 03 658) in which emitter and receiver are disposed within a U-shaped casing, the emitter being lodged in one leg and the receiver being lodged in the other leg of the U-shaped enclosure and the passage of the beams extending vertically between these legs.